>>>Monday Macro/Closeup April 7 - 13, 2014<<<

Galls on plants are often caused by tiny wasps which lay eggs in some part of a plant, causing the plant to form a swollen area which then serves to feed and protect the wasp's developing baby.

Most of these wasps utilize just one species of plant. Here in California, we have a number of them who seek several different oak species. So these pictures are of different plant species, each one with a different wasp which seeks only that plant, one wasp species per plant species:

These are the largest and most spectacular, looking like luscious apples. Later they dry to a tan - and much later turn black, making the tree look ugly.

Here is one with the discarded shells of two hatchlings - sort of like mineature Cicada husks:

There are lots of smaller galls on different Oak species, each with it's own kind. Here are two different ones, each about 1/4" wide:

Not always Oaks! Here's one on a poplar leaf - this particular kind is always just like this - at the base of the leaf:

The galls don't seem to harm the trees much - the poplar leaf fell with the rest, in the fall.

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